This invention relates generally to the field of collapsible reusable shipping containers of the type disclosed in my prior U.S. Pat. No. 3,443,737, granted Apr. 13, 1969, and my prior U.S. Pat. No. 4,252,266, granted Feb. 24, 1981; and more particularly to an improved form thereof.
Shipping containers of this type are primarily used for air and truck transport, where space and weight considerations are of greater importance than the cost of fabrication. In the latter of my above mentioned patents, there is disclosed an improved form in which the conventional wood or synthetic resinuous pallet has been substituted by an integral base element which not only saves a substantial amount of cargo space in the transporting vehicle, but provides a degree of rigidity to the device which is more than adequate quate for most loads provided that the container is not of excessive size.
While the base element provides such rigidity as a result of the gluing of foldable tabs integrally formed with the lower edges of the side walls, and the side walls themselves possess substantial tensil and compressive strength in the plane thereof, when such devices are used for the transportation of relatively heavy particulate loads, the side walls of the container do not always exhibit the desired degree of resistance to outward bulging in response to stresses exerted by the load in planes normal to the planes of the side walls. Under such circumstances, it is possible to increase the thickness of the side walls. However, where more than two plys of corrugation are involved, it becomes increasingly difficult to fold the walls in a manner necessary to place the container in collapsed condition.